[2.6.26-rc7] shrink_icache from pagefault locking (nee: nfsd hangs for a few sec)...

[Daniel J Blueman]

I'm seeing a similar issue [2] to what was recently reported [1] by
Alexander, but with another workload involving XFS and memory
pressure.

SLUB allocator is in use and config is at http://quora.org/config-client-debug .

Let me know if you'd like more details/vmlinux objdump etc.

Thanks,
 Daniel

--- [1]

http://groups.google.com/group/fa.linux.kernel/browse_thread/thread/e673c9173d45a735/db9213ef39e4e11c

--- [2]

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.26-rc7-210c #2
-------------------------------------------------------
AutopanoPro/4470 is trying to acquire lock:
 (iprune_mutex){--..}, at: [<ffffffff802d94fd>] shrink_icache_memory+0x7d/0x290

but task is already holding lock:
 (&mm->mmap_sem){----}, at: [<ffffffff805e3e15>] do_page_fault+0x255/0x890

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&mm->mmap_sem){----}:
      [<ffffffff80278f4d>] __lock_acquire+0xbdd/0x1020
      [<ffffffff802793f5>] lock_acquire+0x65/0x90
      [<ffffffff805df5ab>] down_read+0x3b/0x70
      [<ffffffff805e3e3c>] do_page_fault+0x27c/0x890
      [<ffffffff805e16cd>] error_exit+0x0/0xa9
      [<ffffffffffffffff>] 0xffffffffffffffff

-> #1 (&(&ip->i_iolock)->mr_lock){----}:
      [<ffffffff80278f4d>] __lock_acquire+0xbdd/0x1020
      [<ffffffff802793f5>] lock_acquire+0x65/0x90
      [<ffffffff8026d746>] down_write_nested+0x46/0x80
      [<ffffffff8039df29>] xfs_ilock+0x99/0xa0
      [<ffffffff8039e0cf>] xfs_ireclaim+0x3f/0x90
      [<ffffffff803ba889>] xfs_finish_reclaim+0x59/0x1a0
      [<ffffffff803bc199>] xfs_reclaim+0x109/0x110
      [<ffffffff803c9541>] xfs_fs_clear_inode+0xe1/0x110
      [<ffffffff802d906d>] clear_inode+0x7d/0x110
      [<ffffffff802d93aa>] dispose_list+0x2a/0x100
      [<ffffffff802d96af>] shrink_icache_memory+0x22f/0x290
      [<ffffffff8029d868>] shrink_slab+0x168/0x1d0
      [<ffffffff8029e0b6>] kswapd+0x3b6/0x560
      [<ffffffff8026921d>] kthread+0x4d/0x80
      [<ffffffff80227428>] child_rip+0xa/0x12
      [<ffffffffffffffff>] 0xffffffffffffffff

-> #0 (iprune_mutex){--..}:
      [<ffffffff80278db7>] __lock_acquire+0xa47/0x1020
      [<ffffffff802793f5>] lock_acquire+0x65/0x90
      [<ffffffff805dedd5>] mutex_lock_nested+0xb5/0x300
      [<ffffffff802d94fd>] shrink_icache_memory+0x7d/0x290
      [<ffffffff8029d868>] shrink_slab+0x168/0x1d0
      [<ffffffff8029db38>] try_to_free_pages+0x268/0x3a0
      [<ffffffff802979d6>] __alloc_pages_internal+0x206/0x4b0
      [<ffffffff80297c89>] __alloc_pages_nodemask+0x9/0x10
      [<ffffffff802b2bc2>] alloc_page_vma+0x72/0x1b0
      [<ffffffff802a3642>] handle_mm_fault+0x462/0x7b0
      [<ffffffff805e3ecc>] do_page_fault+0x30c/0x890
      [<ffffffff805e16cd>] error_exit+0x0/0xa9
      [<ffffffffffffffff>] 0xffffffffffffffff

other info that might help us debug this:

2 locks held by AutopanoPro/4470:
 #0:  (&mm->mmap_sem){----}, at: [<ffffffff805e3e15>] do_page_fault+0x255/0x890
 #1:  (shrinker_rwsem){----}, at: [<ffffffff8029d732>] shrink_slab+0x32/0x1d0

stack backtrace:
Pid: 4470, comm: AutopanoPro Not tainted 2.6.26-rc7-210c #2

Call Trace:
 [<ffffffff80276823>] print_circular_bug_tail+0x83/0x90
 [<ffffffff80275e09>] ? print_circular_bug_entry+0x49/0x60
 [<ffffffff80278db7>] __lock_acquire+0xa47/0x1020
 [<ffffffff802793f5>] lock_acquire+0x65/0x90
 [<ffffffff802d94fd>] ? shrink_icache_memory+0x7d/0x290
 [<ffffffff805dedd5>] mutex_lock_nested+0xb5/0x300
 [<ffffffff802d94fd>] ? shrink_icache_memory+0x7d/0x290
 [<ffffffff802d94fd>] shrink_icache_memory+0x7d/0x290
 [<ffffffff8029d732>] ? shrink_slab+0x32/0x1d0
 [<ffffffff8029d868>] shrink_slab+0x168/0x1d0
 [<ffffffff8029db38>] try_to_free_pages+0x268/0x3a0
 [<ffffffff8029c240>] ? isolate_pages_global+0x0/0x40
 [<ffffffff802979d6>] __alloc_pages_internal+0x206/0x4b0
 [<ffffffff80297c89>] __alloc_pages_nodemask+0x9/0x10
 [<ffffffff802b2bc2>] alloc_page_vma+0x72/0x1b0
 [<ffffffff802a3642>] handle_mm_fault+0x462/0x7b0
 [<ffffffff80277e2f>] ? trace_hardirqs_on+0xbf/0x150
 [<ffffffff805e3e15>] ? do_page_fault+0x255/0x890
 [<ffffffff805e3ecc>] do_page_fault+0x30c/0x890
 [<ffffffff805e16cd>] error_exit+0x0/0xa9
-- 
Daniel J Blueman
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